Intelligent power amplifier systems are rapidly promoted in the field of mobile phones due to their dual functions of improving the sound quality of the electrical-acoustic conversion device and protecting the electrical-acoustic conversion device. Intelligent power amplifiers can monitor the amplitude and temperature situations of the voice coil of the electrical-acoustic conversion device in real time and give feedback, realizing the purpose of protecting the electrical-acoustic conversion device. This requires the manufacturers of electrical-acoustic conversion devices to provide accurate maximum amplitude parameter and highest temperature parameter of the voice coil, which parameters break the existing parameter definition method and reliability verification method. In order to cooperate with the intelligent power amplifiers to protect and improve the performance of the electrical-acoustic conversion devices, it requires to verify the rationality of the maximum amplitude parameter Xmax and the highest temperature parameter Tmax of the voice coil.
The traditional verification method is to verify the maximum amplitude parameter Xmax and the highest temperature parameter Tmax of the voice coil respectively.
FIG. 1 shows a solution of verifying the maximum amplitude parameter Xmax. A sweep signal generator 1 generates a traditional sweep signal, a power amplifier 2 amplifies the same and inputs the same into an electrical-acoustic conversion device, an amplitude range finder 3 measures the maximum amplitude to detect whether the maximum amplitude satisfies the maximum amplitude parameter Xmax to be verified. If not, then the gain of the power amplifier unit is increased or reduced until the actual tested maximum amplitude satisfies Xmax. Performance experiment is performed on the electrical-acoustic conversion device after operating for a predetermined period of time with this sweep signal and gain.
FIG. 2 shows a solution of verifying the highest voice coil parameter Xmax. The sweep signal generator 1 generates a traditional sweep signal, the power amplifier 2 amplifies the same and inputs the same into an electrical-acoustic conversion device, a temperature detector 4 tests the temperature of the voice coil to detect whether the temperature of the voice coil satisfies the highest voice coil parameter Tmax to be verified. If not, then the gain of the power amplifier unit is increased or reduced until the actually highest voice coil parameter satisfies Tmax. Performance experiment is performed on the electrical-acoustic conversion device after operating for a predetermined period of time with this sweep signal and gain.
However, the inventors have found that the above method has the following limitations.
(1) During the normal operation of an electrical-acoustic conversion device, both the amplitude and the temperature of the voice coil affect the operation state of the electrical-acoustic conversion device. In the state where the amplitude is maximum and the temperature of the voice coil is highest, the electrical-acoustic conversion device can still operate normally, and such Xmax and Tmax are effective and rational. However, in the traditional verification method, the verification of the amplitude and the verification of the highest temperature of the voice coil are separated and the actual situation cannot be simulated.
(2) In the traditional method, when verifying the amplitude, in order to make the amplitude reach the maximum amplitude parameter Xmax to be verified, the gain of the power amplifier will be increased or reduced, which will inevitably make the temperature of the voice coil increase or reduce, and even the temperature of the voice coil may exceed the tolerable temperature of the voice coil and cause burning. In such a case, it is difficult to determine whether the failure is caused by irrational Xmax or by the affection of the temperature of the voice coil. At the same time, when verifying the temperature of the voice coil, in order to make the temperature of the voice coil reach the highest temperature Tmax of the voice coil to be verified, the gain of the power amplifier will be increased or reduced, which will inevitably make the amplitude of the entire frequency band increase or reduce, and even the amplitude may exceed the tolerable range of the voice coil and cause the voice coil short-circuited. In such a case, it is difficult to determine whether the failure is caused by the irrational highest temperature Xmax of the voice coil or caused by the affection of the amplitude.